Sony BP-HP550-11 Battery - Replacement for Sony BP-HP550-11 Headphone Battery - Compatible with Sony MDR-RF860, MDR-RF4000, MDR-RF970, MDR-RF970RK, MDR-RF925 (700mAh, 2.4V, NI-MH) Replacement Sony BP-HP550-11 Battery Replacement for Sony BP-HP550-11 Headphone Batteries Lifetime Warranty, Compatible with Sony MDR-RF860, MDR-RF4000, MDR-RF970, MDR-RF970RK, MDR-RF925 Capacity: 700mAh, Upstart Battery Brand On Sale for a Limited Time!